Brain Microvascular Endothelial Cell Hyperpermeability Following Traumatic Burn Injury: Role of Caspase‐3 Activation

Abstract

Traumatic burn injury is associated with extravasation of fluid from the intravascular space to the interstitium, abdominal cavity and also leads to blood brain barrier (BBB) disruption and brain edema. We hypothesized that caspase‐3 activation following burn would lead to the proleolytic cleavage of the tight junction associated proteins (TJPs) resulting in BBB hyperpermeability and brain edema. Our objective was to determine if burn injury‐mediated rat brain microvascular endothelial cell (RBMEC) hyperpermeability and cleavage of the TJPs, are caspase‐3 dependent. Male Sprague‐Dawley rats were divided into sham and experimental (40% TBSA scald burn) groups. RBMEC were exposed to sham/burn serum and permeability was assessed with FITC‐dextran.TJP integrity was studied using ZO‐1 and occludin immunofluorescnece. Mitochondrial potential (MTP) was determined using JC‐1 and caspase‐3 activity using a fluorometric assay. Burn serum significantly increased permeability compared to sham (p<0.05), and this effect was prevented by the caspase‐3 inhibitor, Z‐DEVD‐FMK (p<0.05). Burn serum treatment significantly decreased MTP and increased caspase‐3 activity (p<0.05). Burn serum disrupted ZO‐1 and occludin that was prevented by Z‐DEVD‐FMK. These results suggest that burn‐mediated blood brain barrier disruption is mediated by caspase‐3 activation and subsequent cleavage of ZO‐1 and occludin.